Air conditioner with air flow sensor

ABSTRACT

An air conditioning system comprising an air duct for a stream of air flowing therethrough, an air permeable refrigerant evaporator in the duct for chilling the air and an air pressure differential sensor in communication simultaneously with opposite sides of the evaporator for sensing the pressure drop of air passing through the evaporator with the sensor being mounted entirely on the evaporator and supported only thereby. The disclosure also includes the system in which the evaporator is an A-coil and with the sensor being a U-tube with spaced taps therealong located at the apex of the coil with one tube part being on the inside of the A-coil and the other on the outside.

Hafner et al.

[451 Aug. 27, 1974 AIR CONDITIONER WITH AIR FLOW SENSOR Inventors: Robert O. Hafner, Franklin; Richard M. Anderson, Smyrna, both of Tenn.

Heil Quaker Corporation, Lewisburg, Tenn.

Filed: May 21, 1973 Appl. No.: 362,388

Assignee:

References Cited UNITED STATES PATENTS Cole 73/205 L Howland 62/140 3,377,817 4/[968 Pctranek 62/l40 Primary ExaminerMeyer Perlin Attorney, Agent, or Firm-Hofgren, Wegner, Allen,

Stellman & McCord [57] ABSTRACT An air conditioning system comprising an air duct for a stream of air flowing therethrough, an air permeable refrigerant evaporator in the duct for chilling the air and an air pressure differential sensor in communication simultaneously with opposite sides of the evaporator for sensing the pressure drop of air passing through the evaporator with the sensor being mounted entirely on the evaporator and supported only thereby. The disclosure also includes the system in which the evaporator is an A-coil and with the sensor being a U-tube with spaced taps therealong located at the apex of the coil with one tube part being on the inside of the A- coil and the other on the outside.

9 Claims, 3 Drawing Figures AIR CONDITIONER WITH AIR FLOW SENSOR BACKGROUND OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary semi-schematic view partly in section of a heating and air conditioning system embodying the invention.

FIG. 2 is a perspective view showing the refrigerant evaporator means and associated structure.

FIG. 3 is a fragmentary vertical sectional view substantially through the apparatus of the A-coil evaporator of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT As can be seen in FIG. 1 the overall system is of the type designed for the combined heating and air conditioning of a building such as a home. The system includes a lower furnace 11 with an air-duct 12 extending therefrom and provided with an air moving means shown schematically by the blower l3 and electric motor 14 for moving air therethrough as indicated by the flow arrows l5.

In addition to the furnace II the system 10 includes an air conditioning arrangement that has the usual external condenser and compressor unit 15 located externally beyond the walls 16 of the building 17 and an evaporator 18 within the air duct 12 and connected to the unit 15 in the usual manner by piping l9 and 20. The evaporator 18 also has the customary liquid condensate disposal arrangement including a liquid trap conduit 21 leading to a disposal pipe 22.

As can be seen more clearly in FIG. 2 the evaporator 18 is in the form of an A-coil having an apex 23 and downwardly extending side coils 24 diverging downwardly therefrom. The evaporator is provided with the customary end cover plates 25 of which only one is shown in FIG. 2 and mounted on the one cover plate 25 is a locking plate 26 that carries the evaporator fittings 27 including a suction tap 28 with the pressure tap 29 being located on the base of the evaporator forming the drain pan 30 from which the drain conduit 21 leads as previously described and as shown in FIG. I. In order to show the pressure drop of air flowing upwardly through the evaporator A-coil 18 there is provided an air pressure differential sensor means which is here shown as a hairpin tube 32 that is in communication simultaneously with opposite sides of the evaporator 18 as indicated in FIG. 3. This air pressure sensor tube 32 senses simultaneously the air flow characteristics on the two sides of the apex 23 and thus is used to register the pressure drop of air flowing through the evaporator.

The air pressure sensor tube 32 comprises two parallel parts 33 and 34 with the one part 33 being downstream with relation to the air flow above the apex 23 and the other tube part 34 being upstream beneath the apex and therefore within the confines of the upper end of the evaporator.

The tube 32 is in communication simultaneously with opposite sides of the evaporator at the apex 23 by being provided with spaced air holes 35 and 36 along the two parts of the tube.

The sensor is supported entirely on the evaporator 18 as contrasted to prior devices that are supported on the duct-work 12 or other parts of the system. Thus in the illustrated embodiment the sensing portion of the tube which includes the parts 33 and 34 and an interconnecting bight 37 are provided with tubular extensions 38 that extend downwardly along the one cover plate 25 and is held on a mounting bracket 39 secured to the one cover plate 25. These tubular extensions 38 are in themselves not provided with the openings or perforations 35 and 36.

In the illustrated embodiment as shown in FIG. 1 the tube ends 38 are connected by pressure lines 40 and 41 to a slope gauge 42 of the customary type for indicating the pressure drop of the air 15 flowing through the evaporator in inches of water and thereby indicates the rate of air flow.

As can be seen from the above description the air flow sensor of this invention provides the readings of resultant pressures on the high pressure and low pressure sides of the evaporator and thereby provides an average or balancing pressure that is of course directly related to the total pressure differences or pressure drop through the evaporator. This reading may be related to air movement characteristics such as the volumetric flow of air through the system. Furthermore because the air pressure sensor tube 32 spans the entire width of the evaporator it will produce a reading on the gauge 42 that reflects the conditions over the entire area of the evaporator.

One of the very important advantages of this invention is that there is now no necessity to modify the system to accept spaced pressure taps in the system itself as in the duct 12 as the evaporator 18 itself carries the necessary taps for determining theair flow characteristics. Furthermore, the sensor is installed at the factory on the evaporator 18 and therefore this invention eliminates the possibility of any variance due to improper location of the pressure taps as occurs when they are installed in the field. In addition, the use of the A-coil evaporator with the sensor 32 at the apex 23 greatly facilitates the adjusting of the air flow in the system to an adequate level which is shown immediately by the air flow sensor tube 32. This occurs because the coils 24 which are converging relative to the upward flow 15 of air concentrate the air flow at the coil 18 apex 23 so that flow measurements are more precise.

Having described our invention as related to the embodiment shown in the accompanying drawings, it is our intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows:

1. An air conditioning system, comprising: an air duct for confining a stream of air; means for forcing said stream through said duct; an air permeable refrigerant evaporator-in said duct for chilling said air; an air pressure differential sensor means in communication simultaneously with opposite sides of said evaporator means for sensing the pressure drop of air passing through the evaporator; and means for mounting said sensor means entirely on said evaporator and separate from said duct.

2. The air conditioning system of claim 1 wherein said air pressure differential sensor comprises a pressure responsive member having separate parts on said opposite sides of the evaporator means and provided with spaced air access taps extending along each part, each said part substantially spanning said duct.

3. The air conditioning system of claim 2 wherein said pressure responsive member comprises a U-tube comprising tubular parts on said opposite sides connected by an intermediate tubular bight, said taps being spaced along said tubular parts.

4. The air conditioning system of claim 3 wherein said taps comprise openings exposed to said air stream.

posite to that of said air stream flow; an air pressure differential sensor means in communication simultaneously with opposite sidesof said evaporator means at said apex for sensing the pressure drop of air passing through the evaporator; and means for mounting said sensor means entirely on said evaporator and separate from said duct.

6. The air conditioning system of claim 5 wherein said air pressure differential sensor comprises a pressure responsive member having separate parts on said opposite sides of the evaporator means and provided with spaced air access taps extending along each part, each said part substantially spanning said duct.

7. The air conditioning system of claim 6 wherein said pressure responsive member comprises a U-tube comprising tubular parts on said opposite sides connected by an intermediate bight, said taps being spaced along said tubular parts.

8. The air conditioning system of claim 6 wherein said taps comprise openings exposed to said air stream.

9. The air conditioning system of claim 6 wherein said evaporator is provided with bracket means on which said pressure responsive member is mounted. 

1. An air conditioning system, comprising: an air duct for confining a stream of air; means for forcing said stream through said duct; an air permeable refrigerant evaporator in said duct for chilling said air; an air pressure differential sensor means in communication simultaneously with opposite sides of said evaporator means for sensing the pressure drop of air passing through the evaporator; and means for mounting said sensor means entirely on said evaporator and separate from said duct.
 2. The air conditioning system of claim 1 wherein saId air pressure differential sensor comprises a pressure responsive member having separate parts on said opposite sides of the evaporator means and provided with spaced air access taps extending along each part, each said part substantially spanning said duct.
 3. The air conditioning system of claim 2 wherein said pressure responsive member comprises a U-tube comprising tubular parts on said opposite sides connected by an intermediate tubular bight, said taps being spaced along said tubular parts.
 4. The air conditioning system of claim 3 wherein said taps comprise openings exposed to said air stream.
 5. An air conditioning system, comprising: an air duct for confining a stream of air; means for forcing said stream through said duct; an air permeable refrigerant evaporator means in said duct for chilling said air, said evaporator means comprising an A-coil having an apex and side coils diverging therefrom in the direction opposite to that of said air stream flow; an air pressure differential sensor means in communication simultaneously with opposite sides of said evaporator means at said apex for sensing the pressure drop of air passing through the evaporator; and means for mounting said sensor means entirely on said evaporator and separate from said duct.
 6. The air conditioning system of claim 5 wherein said air pressure differential sensor comprises a pressure responsive member having separate parts on said opposite sides of the evaporator means and provided with spaced air access taps extending along each part, each said part substantially spanning said duct.
 7. The air conditioning system of claim 6 wherein said pressure responsive member comprises a U-tube comprising tubular parts on said opposite sides connected by an intermediate bight, said taps being spaced along said tubular parts.
 8. The air conditioning system of claim 6 wherein said taps comprise openings exposed to said air stream.
 9. The air conditioning system of claim 6 wherein said evaporator is provided with bracket means on which said pressure responsive member is mounted. 